Storage devices, such as hard disk drives, include adaptive power management programs that alter the power consumption mode of the disk drive based on current usage of the drive. The disk drive controller or device driver of the hard disk drive executing in the host operating system may adjust the power usage to an active, standby, idle or sleep mode based on the frequency of user access. Computer systems often include a power management program that the user can configure to specify the power consumption mode, e.g., idle, standby or sleep mode based on the length of time since the last received user input. For instance, the Power Options Properties utility provided with the Microsoft Windows operating system provides such capabilities. (Microsoft and Windows are registered trademarks of Microsoft Corporation). Although placing a disk drive in a lower power consumption mode, such as standby, idle or sleep conserves power, such lower consumption modes increases disk latency. If the disk drive is in a low power consumption mode when receiving an Input/Output (I/O) request, latency is experienced while waiting for the disk drive to power-up all components to execute the I/O request. The lower the power consumption mode, the greater the latency and delays that occur to fully power-up the disk components to execute an I/O request received in such power savings mode.
System administrators managing large storage arrays of interconnected hard disk drives may specify power consumption modes for the hard disk drives in the storage array. Typically, the administrator will balance power conservation and latency goals in determining the power consumption mode for the disk drives in the array.